1. Field of the Invention
The invention relates generally to well servicing operations, such as gravel packing operations to complete wells for production operations and to enhance the productivity thereof. More particularly, the present invention concerns a re-enterable well servicing system that is effective for gravel packing operations, gravel washing operations, and other downhole activities. The present invention also concerns a guiding tool that is conveyed through tubing and into a well casing and incorporates a plurality of guide fingers that are formed in the downhole environment to a guiding receptacle configuration to ensure re-entry of well servicing tools throughout the productive period of a well. From the standpoint of gravel packing operations, the guiding tool is connected with a blank pipe and screen assembly, and an inflate packer is set immediately above a gravel column of limited height to permit a production interval of greater height to be produced and thus permit a greater rate of production from the production interval.
2. Description of Related Art
With conventional vent screen gravel packs, a long annular area of a well is filled with gravel (sand), with the gravel serving to permit the flow of production gas through the gravel and through a through tubing gravel pack (TTGP) screen and into a vent pipe where the flowing gas is conducted above the gravel pack and to the production tubing of the well. The height of the column of gravel in the annulus must be sufficiently great to prevent gas migration through the gravel in the annulus between the well casing and the vent pipe so that production flow occurs only through the gravel pack screen and vent pipe to the production tubing string. The typically significant height of the gravel column in gravel pack well completions limits production capability and also causes the potential loss of a large productive interval (typically 150 feet) since the completions are not retrievable.
If the height of the gravel pack column above the TTGP screen and above the casing perforations is insufficient, i.e., less than about 150 feet, and the well is produced at a relatively high flow rate, the gravel (sand) that is located within the annulus between the TTGP screen and the vent pipe and the well casing will not completely isolate the gas pressure of the productive formation. Rather, the gas will migrate through the gravel column and will entrain some of the gravel, thus carrying it upwardly into the production tubing. In this manner, some of the gravel is produced along with the flowing gas, thus reducing the height of the gravel column and interfering with the productive capability of the well.